1. Field of the Invention
The present invention relates to an optical disc having an area that is recordable and reproducible (the xe2x80x9crewritable areaxe2x80x9d below), and an area that is only reproducible (the xe2x80x9cread-only areaxe2x80x9d below).
2. Description of the Prior Art
The problem that arises when there are both rewritable and read-only areas on an optical disc is how the boundary between the rewritable area and the read-only area is determined. If the two areas are too close at the boundary therebetween, mixing of data from the two area may occur; if the areas are too separated, the efficiency of using the optical disc may deteriorate.
The object of the present invention is therefore to resolve the above problem and provide a new optical disc whereby positioning conditions for the border area between a rewritable area and read-only area are defined so that mixing data from both areas does not occur, and the rewritable area and read-only area are positioned substantially adjacent, or via a land having a predetermined width, so that the efficiency of using the optical disc does not deteriorate.
To achieve the above objects, an optical disc according to the first aspect of the invention comprises:
a rewritable area having a single spiral recording track formed by forming a groove and a land circumferentially on a disc substrate with the groove and land alternating and the recording track of a groove corresponding to one circumference of the disc and the recording track of the land corresponding to one circumference of the disc connecting alternately to each other at a particular radial transition line, and the track pitch Pa of the recording tracks is a value less than xcex/NA, said rewritable area having a first data recording area for recording data by marks formed thereon by a local physical change effected in a recording film by a laser beam of wavelength xcex using a lens of a specific aperture NA, and
a read-only area having a second data recording area to which particular information is prerecorded by forming a series of pits on the optical disc to a spiral recording track of a track pitch Pb substantially equal to the track pitch Pa of the spiral recording track in the rewritable area,
said rewritable area comprising recording sectors each of which comprises a first header area preformatted with embossed pits expressing an address information, and a first data recording area for recording data,
said first header area comprising a physical address area PID comprising at least an address area Pid for storing sector address information, said physical address area PID being repeated 2K (K being a positive integer) times,
wherein when the 2K physical address areas PID are labelled in sequence from the first PID1, . . . , PIDK, PIDK+1, . . . , and PID2K, the first half PID1, . . . , PIDK are deviated in a first radial direction of the disc approximately Pa/2 from the track of the groove recording sector, and the second half PIDK+1, . . ., PID2K are deviated in a second radial direction of the disc approximately Pa/2 from the track of the groove recording sector,
said rewritable area comprising a single spiral pattern of start track land at a leading edge, and a single spiral pattern of end track land at a trailing edge, whereby portions of the physical address area PID deviated approximately Pa/2 from the track of the rewritable area are being intruded into the start track land and the end track land.
By the first aspect of the invention, the border between a rewritable area and read-only area in an optical disc always comprises a start track land or a end track land on the rewritable area side adjacent to the boundary line, the surface level of said land being the same as the level of the read-only area side of the boundary line. As a result, the boundary line between the rewritable area and read-only area will never contact a groove. It follows that recording marks in a groove in the rewritable area will not be mistakenly mixed with embossed marks in the read-only area.
The portions of the physical address area PID displaced approximately Pa/2 from the track of the rewritable area are being intruded into the start track land or the end track land. Thus, such deviated portions will not intrude into the read-only area. Thus, there will be no cross-talk between the data in the physical address area PID and the embossed marks of the read-only area.
In the second aspect of the invention, an optical disc of the first aspect further comprises an additional land of a predetermined width disposed between the start track land and the adjacent read-only area, and another additional land of a predetermined width disposed between the end track land and the adjacent read-only area.
By the second aspect of the invention, by inserting the additional land the cross-talk between the rewritable area and read-only area can be prevented. Also, since the additional land is provided it is not necessary to adjust the alignment between the track of the rewritable area and that of the read-only area. Furthermore, by detecting the additional land, it is possible to discriminate between the rewritable area and read-only area.
In the third aspect of the invention, an optical disc of the first aspect is arranged such that the rewritable area and read-only area are formed at least in the lead-in area at the center-side of the optical disc, said read-only area being a control data zone to which control data is prerecorded.
By the third aspect of the invention, the rewritable area and read-only area are formed at least in the lead-in area at the center of the optical disc. Thus, in the read-only area used as the control data zone, it is possible to add a control data which prohibits writing any data in the start track or end track land.
In the fourth aspect of the invention, the optical disc of the third aspect is arranged such that said control data includes data for prohibiting recording any data in said start track and end track lands.
By the fourth aspect of the invention, data read from the read-only area will not be mixed with data from the rewritable area, because absolutely no data is written to the start track or end track land.
In the fifth aspect of the invention, the optical disc of the first aspect is arranged such that the transition between the rewritable area and read-only area occurs approximately at a transition line.
By the fifth aspect of the invention, the leading edge of every track in the rewritable area and the read-only area are aligned along the transition line. Thus, and it is possible to easily seek the tracks and to manage the tracks. Also, it is possible to easily find location where the transition between the rewritable area and read-only area occurs.
In the sixth aspect of the invention, the optical disc of the first aspect is arranged such that the wavelength xcex of the laser beam is 650 nm, the lens aperture NA is 0.6, and track pitch Pa and track pitch Pb are both 0.74 xcexcm, and wherein a modulation method used is method modulating 8 data bits to 16 channel bits with the shortest recording mark being three channel bits and the longest recording mark being 11 channel bits.
By the sixth aspect of the invention, a compact, efficient data format that does not waste disc space is thus also achieved.
In the seventh aspect of the invention, an optical disc comprises:
a rewritable area having a single spiral recording track formed by forming a groove and a land circumferentially on a disc substrate with the groove and land alternating and the recording track of a groove corresponding to one circumference of the disc and the recording track of the land corresponding to one circumference of the disc connecting alternately to each other at a particular radial transition line, and the track pitch Pa of the recording tracks is a value less than xcex/NA, said rewritable area having a first data recording area for recording data by marks formed thereon by a local physical change effected in a recording film by a laser beam of wavelength xcex using a lens of a specific aperture NA, and
a read-only area having a second data recording area to which particular information is prerecorded by forming a series of pits on the optical disc to a spiral recording track of a track pitch Pb substantially equal to the track pitch Pa of the spiral recording track in the rewritable area,
said rewritable area comprising recording sectors each of which comprises a first header area preformatted with embossed pits expressing an address information, and a first data recording area for recording data,
said first header area comprising a physical address area PID comprising at least an address area Pid for storing sector address information, said physical address area PID being repeated 2K (K being a positive integer) times,
wherein when the 2K physical address areas PID are labelled in sequence from the first PID1, . . . , PIDK, PIDK+1, . . . , and PID2K, the first half PID1, . . . , PIDK are deviated in a first radial direction of the disc approximately Pa/2 from the track of the groove recording sector, and the second half PIDK+1, . . . , PID2K are deviated in a second radial direction of the disc approximately Pa/2 from the track of the groove recording sector, and
said rewritable area being disposed adjacent to said read-only area with a land having a width approximately equal to a plurality of tracks being interposed therebetween.
In the eighth aspect of the invention, an optical disc comprises:
a rewritable area having a single spiral recording track formed by forming a groove and a land circumferentially on a disc substrate with the groove and land alternating and the recording track of a groove corresponding to one circumference of the disc and the recording track of the land corresponding to one circumference of the disc connecting alternately to each other at a particular radial transition line, and the track pitch Pa of the recording tracks is a value less than xcex/NA, said rewritable area having a first data recording area for recording data by marks formed thereon by a local physical change effected in a recording film by a laser beam of wavelength xcex using a lens of a specific aperture NA, and
a read-only area having a second data recording area to which particular information is prerecorded by forming a series of pits on the optical disc to a spiral recording track of a track pitch Pb substantially equal to the track pitch Pa of the spiral recording track in the rewritable area,
wherein said transition between the rewritable area and read-only area occurs approximately at a transition line.
In the ninth aspect of the invention, an optical disc of the eighth aspect is arranged such that the groove pitch of the rewritable area is twice the pitch of the embossed marks of the read-only area.
By the ninth aspect of the invention, it is possible to record data to the rewritable area at substantially the same recording density used in the read-only area.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.